Typically, gas turbine engines include a compressor for compressing air, a combustor for mixing the compressed air with fuel and igniting the mixture, and a turbine blade assembly for producing power. Combustors often operate at high temperatures that may exceed 2,500 degrees Fahrenheit. Typical turbine combustor configurations expose turbine blade assemblies to these high temperatures. As a result, turbine blades must be made of materials capable of withstanding such high temperatures. In addition, turbine blades often contain cooling systems for prolonging the life of the blades and reducing the likelihood of failure as a result of excessive temperatures.
Typically, turbine blades are formed from a root portion at one end and an elongated portion forming a blade that extends outwardly from a platform coupled to the tip at an opposite end of the turbine blade. The blade is ordinarily composed of a tip opposite the root section, a leading edge, and a trailing edge. One particular turbine blade design has a cavity positioned generally in central portions of the turbine blade and extending from the tip towards the root of the blade. Inner aspects of the outer wall forming the turbine blade contain an intricate maze of cooling channels forming a cooling system. The cooling channels receive air from the compressor of the turbine engine, pass the air through the blade root and cooling channels, and exhaust the cooling air from the blade. The cooling channels often include multiple flow paths that are designed to maintain all aspects of the turbine blade at a relatively uniform temperature.
The turbine blades are typically coupled to a disc of a turbine blade assembly that rotates about a rotational axis. The turbine blades extend from the disc of the turbine blade assembly such that the tips of the blades are positioned very close to an outer seal attached to the casing of the turbine engine. The outer seal does not rotate, but instead, remains stationary. As the temperature of the turbine engine increases, the turbine blades and the seal expand. Thus, a gap exists between the blade tips and the outer seal at rest and at design temperatures. Combustion gases flow between the turbine blades and between the blade tips and the seal. The gas flow between the turbine blades is referred to as primary flow, and the flow of gases outward from the lower span of the blade towards the blade tip is referred to as secondary flow. Combustion gases that flow between the blade tip and the outer seal are referred to as leakage gases because these gases are bypassing the turbine blades and not assisting the blades in rotating about the rotational axis. The greater the amount of leakage gases flowing between the blade tips and the outer seal, the more inefficient a turbine engine. Thus, a need exists for a turbine blade that effectively reduces the flow path of leakage gases between blade tips of a turbine blade assembly and an outer seal.